Pole shader



' April 22 ,-19z4. 1,491,386

7 J. B. FORD POLE SHADER Filed June 22. 1921 lh\/entor". I John BF'or'd,

His Attorney.

Patented Apr. 22, 1924.

, UNITED STATES I v "1,491,386 PATENT OFFICE.

. JOHN. B..FORD, OF SCHENEGTADY, NEW YORK, ASSIGNOR T GENERALTELEC'IFRIIC COMPANY, A CORPORATION OF NEW YORK.

POLE snaman.

Application filed June 22, 1921. Serial No. 479,600.

To all whom it may concern:-

Be it known that 1, JOHN B. FORD, a

citizen of the United States, residing at Schenectady, county ofSchenectady, State 6 of New York, have invented certain new and usefulImprovements in Pole Shaders, of which the following is a specification.It is common practice to. provide pole shaders of copper or other goodconducting 10 material for the purposeof setting up in a magneticstructure for alternating current apparatus, a magnetic flux which isdisplaced in phase from the main flux through the structure so as tothereby have the flux in the structure maintained while the main flux ispassing through the zero value. For example, such pole shaders have beenused in alternating current switches to prevent chattering by setting'up a maintaining flux displaced in phase from the main flux, themaintaining flux serving to magnetically hold the movable magneticmember of the switch during the time while the alternations of the mainflux pass through the zero value. Such pole shaders have a disadvantagein that a substantial portion of the pole faceof the magnetic structuremust be cut away in order to accommodate the pole shader, and theeffective area of the pole face is thereby materially reduced sincecopper is nonmagnetic.

One of the objects of my invention is to provide a pole shader which isnot only electrically conductive, but also has magnetic-properties, sothat the entire area of the pole face in which the pole shader isembedded shall be effective in carrying the lines of magnetic flux.

In order for the pole shader to have the greatest effect in setting up adisplaced magnetic flux, the resistance of the pole shader should beapproximately equal to the reactance thereof, and I have found thatsteel has the desired properties, although my invention is notnecessarily limited to pole shaders of steel.

The magnetic structure of an alternating current device is ordinarilymade up of laminations of magnetic material, and some means must beprovided for holding the laminations together. Iron bolts or pins arecustomarily used for that purpose, since the iron bolts or pins are alsomagnetic.

Another of the objects of my invention isto provide a pole shader whichis held in place by the means for holding the laminations of themagnetic structure together. The pole shader is thereby securely held inplace and becomes for all practical purposes an integral part of themagnetic structure.

For a better understandingof my invention, reference is had to theaccompanying drawing which shows an embodiment of my invention forpurposes of illustration, and in which Fig. 1 showsthe operatingelectromagnet of an alternating current electromagnetic switch with twopole shaders incorporated therein, in accordance with my invention; Fig.2.-is a perspective detail the pole I 13 mounted on one of the poles ofthe magnetic structure. ing apart of the magnetic structure is amagnetic movable element, an armature 14, which is supported in a cradle15 so. that the armature will accurately align itself with the polefaces of the magnetic structure. The cradle support 15 is pivotallymounted in a support 16 and is adapted to "operate a shaft 17 to whichswitch mechanism or other devices to be operated by the electromagnetare connected. While I have shown a pole shader on each pole of themagnetic structure, my invention is not necessarily limited thereto,since a single pole shader will have beneficial results in maintainingthe armature of the electromagnet attracted duringthe time that the,main flux of the electromagnet is passing through the zero "value. Forswitches in which a cradled armature or other movable magnetic member isprovided for cooperation with a U-shaped magnetic structure, I find itadvisable, although not necessary, to employv a pole shader embeddedinthe end of each leg of the magnetic structure.

' The pole shader is embedded in the laminated magnetic structure so asto be at right Associated with and formnetic and electric conductingmaterial, and

the resistance thereof is predetermined so as to be substantially equalto the reactance thereof. I have found that steel has the desirablequality of not only being magnetic, but also has a sufiiciently highresistance so that the reactance of the pole shader will besubstantially equal to the resistance.

' This pole shader will set up a magnetic flux which is angularlydisplaced with respect to the main flux set up in the magnetic structuredue to the energization of the winding 13 so as to magnetically hold thearmature 14 during the time that the main flux is passing through thezero value. By reason of the fact that the pole shader has a resistancewhich is substantially equal to the reactance thereof, the pole shaderwill have the maximum effect in setting up a suitably displaced magneticmaintaining flux.

The pole shader is provided with angularly disposed ears 18 and 19 whichembrace the sides of the pole and provide means for holding the poleshader in place in the magnetic structure. Each of the ears 18 and "19is provided with an aperture through which the iron bolt or pin 20 isadapted to pass, so as to hold the pole shader in position in themagnetic structure, and also for the purpose of holding the laminationsof the magnetic structure together. It will be seen that the effectivearea of the pole face of the magnetic structure has not been lessened inany way because of the provision of the pole shader. That is because ofthe fact that the pole shader is of magnetic material. It is also to benoted that the pole shader can be put in place on the pole of themagnetic structure and then filed so as to be exactly flush with thesurface formed by the ends of the laminations of the magnetic structure.An accurate alignment of the armature 14 with respect to the surface ofthe magnetic structure is thereby made possible. The pole shader when inposition on the pole of the magnetic structure becomes substantially anintlegral part of the magnetic structure.

e pole shader isvery effective in preventing the noise or chatteringwhich occurs in alternating current dew ices. This is due to the factthat the pole shader sets u a very substantial dephased magnetic hol mgflux and also from the fact that the ole shader and the laminations aresecurely eld to ether by the rivet or bolt 20.

n Fig. 4, I have shownan alternative netic pole and the flux set upmethod of mounting the pole shader in position, and it will be seen thatin this case the pole shader does not have the same proportion of thetotal of the pole surface included within the pole shader as in the caseof the pole shaders of the 'other fi res. The reactanceof the. poleshader in ig. 4. will necessarily be less than the reactance of the'poleshader as shown in Fig. 2. The resistance, however, will be the same andit will be understood from this by those skilled in the art the mannerin which the pole shader maybe adjusted in position so as to have thedesired reactance. It will be understood by those skilled in the art themanner in which the resistance of the pole shader may be varied. Theadjustment of the proper reactance for the pole'shader will bedetermined by testing the effort required to pull the armature 14 awayfrom the pole pieces.

The ears 18 and 19 of the pole shader have a distinct effect in settingup the dephased magnetic flux. That is because of the fact that theseears, together with the pin 20, cause eddy currents to be set u in the mcurrents is also dephased from t e main flux and thus assist dephasedflux set up by the main flat part of t e pole shader.

In accordance with the provisions of the patent statutes, I havedescribed the principle of operation of my invention, together with theapparatus wh1ch I now consider to represent the best embodiment thereof,but I desire to have it understood that the apparatus shown is onlyillustrative and that the invention can be carried out by other means.

What Iclaim as new and desire to secure by Letters Patent of the UnitedStates, is,-

1. In combination, a magnetic structure having a winding thereon and apole shader in the pole face of said structure, the said pole shaderhaving a resistance which is substantially equal to the reactancethereof.

Y 2. A pole shader having a main part consisting of aband having ears onthe ends thereof angularly disposed to the said main part for embracingthe sides of a pole of magnetic material to hold the pole shader inposition on the pole.

3. In combination, a magnetic structure, and a pole shader thereonhaving a. main part consisting of a band and an ear on each end thereofangularly disposed to the said main part for embracing the sides of thepole of the said magnetic structure, the said ears having aperturestherein, and a pin of flux which assists the de based flux of the saidmain part of the poo shader.

these ed y osition on the 4. The combination in an electromagneticdevice of a magnetic structure comprising a core and a movable memberarranged to be magnetically attracted into engagement with a ole surfaceof the said core, and a steel po e shader embedded in the said structureand forming a part of the engaging surfaces of the said member and core,the said pole shader having a resistance which is substantially equal tothe reactance thereof.

5. The combination in an electromagnetic device of a. laminated magneticstructure, a.

steel pole shader, having a resistance substan-t tially equal to thereactance thereof, embedded 1n and surrounding a portion of the polesurface of said structure, the said pole shader having angularlydisposed ears on the ends thereof which embrace the sides of thepole,the said ears having a rtures therein, and a bolt which passes t roughthe said apertures for holding the pole shader in position on the saidpole and for holding the laminations of said structure together. Inwitness whereof, I have hereunto set my hand this 21st day of June,1921.

JOHN B. FORD.

